Pyridin-l-oxid

In the other extreme, ethyl 3-oxohexanoate 75 required fusion with 3-pyridyl-hydrazide 73a or 3-hydrazinocarbonyl-pyridine-l-oxide 73b at 120°C in order to give the corresponding pyrazol-3-ones 76a,b (92AF1350) (Scheme 22). Depending on the reaction conditions, the reaction of ethyl 3-oxo-3-phenylpropanoate 77 and cyanomethylhydrazide 78 gave different products. Thus, fusion at 140°C gave pyrazol-3-one 79 and N,A -bis(cyanoacetyl)hydrazine 80, while heating in ethanol... 

Katritzky et al.509 have also made a kinetic study of the deuteration of substituted pyridine-l-oxides (Table 147). For the 2,4,6-trimethyl compound, the rate-acidity profile shows the conjugate acid to be reacting. The slope of the plot, however, was less (0.33) than that (0.56) obtained for 2,4,6-trimethylpyridine... 

Pyridin-l-oxid wird mit Hefe glatt zum Pyridin reduziert2. Aus Nitroso-benzolen wer-den mitHilfe vonHefen N-Phenyl-hydroxylamine bzw. Aniline4 (z. B.aus4-Nitro-so-phenol 40% d.Th. 4-Amino-phenol) erhalten. 

Unsymmetrical as well as symmetrical anhydrides are often prepared by the treatment of an acyl halide with a carboxylic acid salt. The compound C0CI2 has been used as a catalyst. If a metallic salt is used, Na , K , or Ag are the most common cations, but more often pyridine or another tertiary amine is added to the free acid and the salt thus formed is treated with the acyl halide. Mixed formic anhydrides are prepared from sodium formate and an aryl halide, by use of a solid-phase copolymer of pyridine-l-oxide. Symmetrical anhydrides can be prepared by reaction of the acyl halide with aqueous NaOH or NaHCOa under phase-transfer conditions, or with sodium bicarbonate with ultrasound. 

In II and III the Hg coordination is different from that shown (2 or 3 coordination) in complexes of Hg(I) with N-donor ligands (see 8.2.4.2.3). In II, three of the four pyridine-l-oxide molecules bridge adjacent Hg-Hg units, giving the Hg atom a coordination number of 4 or 5, whereas in III there are 4-coordinated Hg atoms. Attempts to prepare analogous complexes with Ph3AsO lead to disproportionation products . 

Analogous to its reaction with carbonyl compounds (see 6.3.4), benzyltrimethyl-silane undergoes a fluoride-induced nucleophilic substitution reaction on pyridine-1-oxides and quinoline-l-oxide to form 2-benzylpyridines (>70%) and 2-benzyl-quinoline (65%), respectively [57], Allyltrimethylsilane reacts with pyridine-l-oxide to produce 2-propenylpyridine (56%). 

C. K. Lowe-Ma, R. A. Nissan and W. S. Wilson, Tetrazolo[l,5-a]pyridines and Eurazano[4,5-b]pyridine-l-oxides as Energetic Materials, NWC TP 6985 (1989), Naval Weapons Center, China Lake, CA. 

Reaction of 6-nitro[l,2,3]oxadiazolo[4,5- ]pyridine-l-oxide 8 under Diels-Alder conditions resulted in the formation of several adducts, a normal Diels-Alder adduct, a hetero-Diels-Alder adduct, and a di-adduct, which is believed to arise from the minor dinitroso tautomer of 8 unfortunately, no yields were reported for these products (Equation 5) <2000JOC7391>. 

Oxidative Dimerisierungen von Benzimidazolen mit Pyridin-l-oxid zu 2,2 -Bi-(benzimidazo-lylen) werden durch Palladium katalysiert. 

Die Reaktion von Pyridin-l-oxid mit Phenyl-isocyanat in Dimethylformamid ergibt unter Abspaltung von Kohlendioxid 2-Anilino-pyridin (77%) In ahnlicher Weise erhalt man l-Anilino-isochinolin (75%) ... 

E. 4-Methoxy-2-[[(i S)-(5-methoxy-lid-benzimidazole-2-yl)sulfinyl] methyl]-3,5-dimethyl-pyridine-l-oxide... 

While it has been known for some time that pyridine-1-oxides are protonated on oxygen (Gardner and Katritzky, 1957), amino-pyridine-l-oxides have attracted more attention recently. Using the Hammett equation, it was concluded that the cation of 3-amino-pyridine-1-oxide was an equilibrium mixture of O- and N-protonated forms in the ratio 8 1 (Jaffe, 1965). A similar conclusion was reached for 3-dimethylaminopyridine-l-oxide (Forsythe et al.,... 

Ethoxy- -nitril VIII, 341 Pyridin-l-oxid 3,4,5,6-Tetrahydro-... 

Chlor-4-methyl-5-nitro- X/l, 587 Pyridin-l-oxid 2-Carboxy-4-chlor-5-methyl- E19d, 606 (H -> Li/+ C02)... 

Dichlor-benzyl)- E16a, 221/236 (N-Deacylier.), 245 (O-Alkylier., N-Deacylier.) Pyridin-l-oxid 2,6-Dichlor-3,4-dimethyl- EI9d, 606 (H - Li/ + Cl2)... 

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